text: /**
   * Copyright 2004-present, Facebook, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #pragma once
  
  #include <profilo/LogEntry.h>
  #include <profilo/entries/Entry.h>
  #include <profilo/entries/EntryType.h>
  #include <atomic>
  
  #include "PacketLogger.h"
  
  #define PROFILOEXPORT __attribute__((visibility("default")))
  
  namespace facebook {
  namespace profilo {
  
  using namespace entries;
  
  class Logger {
   public:
    struct EntryIDCounter {
      EntryIDCounter(int32_t initialValue) : id_(initialValue) {}
      EntryIDCounter(EntryIDCounter& copy) = delete;
  
      int32_t next() {
        int32_t value, newValue;
  
        do {
          value = id_.load();
          if (value <= 0 || value == std::numeric_limits<int32_t>::max()) {
            // explicitly handle overflow and skip negative IDs.
            newValue = 1;
          } else {
            newValue = value + 1;
          }
        } while (!id_.compare_exchange_weak(value, newValue));
  
        return value;
      }
  
     private:
      std::atomic<int32_t> id_;
    };
  
    static constexpr size_t kMaxVariableLengthEntry = 1024;
    // Start first entry shifted to allow safely adding extra entries to the trace
    // after completion.
    static constexpr int32_t kDefaultInitialID = 512;
  
    static EntryIDCounter& getGlobalEntryID();
  
    template <class T>
    int32_t write(T&& entry) {
      if (entry.id == 0) {
        entry.id = entryID_.next();
      }
  
      using U = std::decay_t<T>;
      auto size = U::calculateSize(entry);
      char payload[size];
      U::pack(entry, payload, size);
  
      logger_.write(payload, size);
      return entry.id;
    }
  
    template <class T>
    int32_t writeAndGetCursor(T&& entry, TraceBuffer::Cursor& cursor) {
      if (entry.id == 0) {
        entry.id = entryID_.next();
      }
  
      using U = std::decay_t<T>;
      auto size = U::calculateSize(entry);
      char payload[size];
      U::pack(entry, payload, size);
  
      cursor = logger_.writeAndGetCursor(payload, size);
      return entry.id;
    }
  
    PROFILOEXPORT int32_t
    writeBytes(EntryType type, int32_t arg1, const uint8_t* arg2, size_t len);
  
    // This constructor is for internal framework use.
    Logger(logger::TraceBufferProvider provider, EntryIDCounter& counter);
  
   private:
    EntryIDCounter& entryID_;
    logger::PacketLogger logger_;
  
    Logger(const Logger& other) = delete;
  };
  
  } // namespace profilo
  } // namespace facebook
  